In a situation where an officer is forced to make a split second decision for example when in pursuit, what are the ramifications of that decision in relation to accountability of that officer, with an example?
I'm not sure there is a "one size fits all" answer to your response, other than the officer is expected to conduct himself in a reasonable manner. That means there are a number of questions to be asked. What is the nature of the pursuit; is it a traffic violation, or a dangerous escaped felon? What is the vicinity? Is it a deserted road or a community where small children are present.
Many police departments have policies which prohibit officers from engaging in high speed chases except in the most extreme circumstances. The danger of an accident or harm to an innocent bystander is simply too great. Either the officer himself may precipitate an accident, or he may force the person pursued to drive at a higher rate of speed.
So, bottom line, an officer in pursuit must use the same good judgment and conduct himself in the same reasonable manner as would an ordinary person. He is not entitled to take unnecessary risks or increase the risk of harm to another simply because he is a law enforcement officer.